Bottlenose dolphins in Barataria Bay are showing signs of severe ill health, according to NOAA marine mammal biologists and their local, state, federal and other research partners, NOAA announced today. Barataria Bay received heavy and prolonged exposure to oil during the 2010 Gulf spill after the Deepwater Horizon rig exploded.

The NOAA conclusion is based on the results of comprehensive physicals given to 32 live dolphins from Barataria Bay during the summer in 2011. Preliminary results show many of the dolphins were underweight, anemic, had low blood sugar and/or some symptoms of liver and lung disease. Nearly half also had abnormally low levels of the hormones that help with stress response, metabolism and immune function.

Researchers fear that some of the study dolphins are in such poor health that they will not survive, said a NOAA release issued today. One of those dolphins, last observed and studied in late 2011, was found dead in January 2012.

"The results presented today only reflect what we know about the health of dolphins in Barataria Bay area of Louisiana," NOAA spokesman Ben Sherman said in a news release following a teleconference announcing the results. "They may provide possible clues to other dolphins exposed to oil in the northern Gulf of Mexico. However, it is too soon to tell how the Barataria Bay findings apply to the overall (unusual mortality event) or to the health implications for other dolphins exposed to oil in the Gulf of Mexico."

NOAA and its research partners started the Barataria Bay study in 2011 as part of the Natural Resource Damage Assessment, required under the Oil Pollution Act of 1990.

NOAA is sharing the preliminary results from the study so that stranding responders and veterinarians can better care for live stranded dolphins and look for similar health conditions, the news release said.

Scientists have been tracking health concerns for bottlenosed dolphins along the coast of the northern Gulf of Mexico since February 2010. More than 675 dolphins hae been stranded during that time from Franklin County, Florida, to the Louisiana/Texas border, a much higher rate than the usual average of 74 dolphins per year.

The increased death rate prompted NOAA to declare an Unusual Mortality Event, and to investigate the cause of death for as many of the dolphins as possible. All but a few of the stranded dolphins were dead. NOAA said 33 were found alive and seven were taken to marine facilities for rehabilitation.

In the spring, it's typical to see some newborn, fetall and stillborn dolphins strand, but there also has been an increase in strandings of this younger age class during this event in 2010 and 2011. But the deaths are occurring in all age classes at high levels, NOAA said.

In October, NOAA said tests of five of the dead dolphins indicated they were infected with brucellosis, a bacterial infection better known in the United States for killing cattle, bison and elk.

At the time, pathology experts contracted by NOAA to conduct the studies said they didn't know whether oil spilled from the BP Macondo well played a role in the brucellosis deaths, or in the other strandings. But they said oil exposure may have reduced the animals' ability to fight off the disease.

No similar large stranding event involving dolphins has been connected to the Brucella bacteria anywhere else in the world, the scientists said, although the bacteria is often found in dolphins and other marine mammals.

Louisiana officials said the findings were not unexpected.

"As NOAA researchers pointed out, the dolphins' symptoms are consistent with those seen in other mammals exposed to oil," said Coastal Protection and Restoration Authority chairman Garret Graves, who acts as the Louisiana trustee in the damage assessment process. "The Deepwater Horizon oil spill released nearly 5 million barrels of oil into the Gulf of Mexico off our coast.

"We will continue to participate in the Unusual Mortality Event (research) in response to stranded dolphins and whales, as well as the ongoing Natural Resource Damage Assessment, as we work to understand the full scope of damages to our natural resources," Graves said. "These findings demonstrate that it is absolutely crucial for BP to continue to fund assessment activities."